Investigation of different surface treatment parameters in the context of roll bonding processes

摘要

High-strength sheet material can be fabricated by using the technology of accumulative roll bonding (ARB). The ARB-process includes a surface treatment of those surfaces which attach to one another during bonding. Surface preparation is followed by stacking and subsequently rolling of the sheets. The objective of the surface treatment is to clean it and to reduce the oxide layer that forms especially on aluminum alloys. Additionally, it increases the roughness of the surface. It is well known that the increased roughness and a minimum oxide layer show a positive impact on the bond strength between the single layers of the multilayered sheet. However, there is no systematical investigation on surface roughness generated by the use of different brushing parameters. The mechanical surface treatment described in this paper is conducted with an automatized brushing machine instead of a brushing tool which needs to be handled manually. The experiments are performed by using three different cylindrical brushes which differ from the brush type. Furthermore, the throughput speed and the brushing pressure are systematically varied. The material used in this investigation is the precipitation hardening aluminum alloy AA6014. After the brushing process the surface of the treated sheets is analyzed with regard to different roughness parameters and the surface topography. Finally, the hypothesis of being able to create a reproducible surface treatment using the brushing machine is reviewed and the significant process parameters are identified.